Mild detergent and method of making same



Patented May 22, 1951 UNITED STATES PATENT OFFICE MILD DETERGENT AND METHOD OF MAKING SAME No Drawing. Application July 19, 1946, Serial No. 684,791

13 Claims. 1

The present invention relates to an improved detergent and method of making the same, and in particular to the composition and preparation of a soap suitable for use on especially sensitive skins and also for use in salt or hard waters.

In the prior art, numerous mild soaps have been compounded, as have numerous detergents for use in hard and salt waters. Of the mild preparations for cleansing the skin, castile soap is extremely well known. However, even this widely known soap has been found unsatisfactory for use on some sensitive skins. of the salt water soaps, those employing coconut oil have been widely used but have proven irritating to the epidermis of many persons.

Among the factors which determine the mildness of a soap may be included the molecular weight and degree of saturation of the fatty acyl radicals present and the alkalinity of the product. Of the saturated fatty acids, those of lower molecular weight have been found to be far more irritating than the higher molecular weight acids. Fatty acid compounds have been shown to produce more irritation of the skin in the presence of an alkali. Of the unsaturated fatty acids, it is also known that the higher the proportion of unsaturated compounds, the greater are the skin irritating characteristics. In this connection, while castile soap contains no low molecular weight saturated fatty acid groups, it does include high molecular weight unsaturated acid compounds and the unsaturated substances are apparently responsible for the allergic manifestations produced in some persons by this form of detergent, The irritating qualities of coconut oil soaps are readily accounted for by the presence of a large proportion of alkyl radicals having fewer than 16 carbon atoms. The average human skin has been found to be slightly acid with a pH value of about 5.5 to 6.5; and it has been established that with otherwise similar detergents the more alkaline are more irritating to skin.

In his copending application of common assignee, Serial No. 493,107, filed July 1, 1943, now U. S. Patent No. 2,414,452, granted January 21, 1947, Joseph Cunder discloses improved mild salt water soaps. These soaps were produced by blending alkali soaps of saturated fatty acids having at least 16 carbon atoms in the molecule with the sulfation products of unsaturated fatty acids also having at least 16 carbon atoms in the molecule or alternatively, by saponifying a blend 'of the saturated fatty acids and the sulfated material. The sulfation was not carried out in the presence of the saturated fatty acids, for these were later mixed with the sulfation product. Cunder appreciated that unsaturated soaps and soaps containing fewer than 16 carbon atoms in the acyl radical are irritating to sensitive skins, and succeeded in sulfating his compositions to 15.5% S03 based on the dry Weight of the oleic acid.

An object of the present invention is to provide an improved detergent which is of extremely mild nature and suited for use in hard or salt waters.

A second object of the invention is to provide a detergent composition containing only a minimum of constitutents which irritate human skin, namely, alkali salts of short-chain fatty acids, alkali salts of long-chain unsaturated fatty acids and high alkalinity.

A third object of the invention is to provide a detergent capable of producing abundant lather or foam at pH values ranging from 7.5 to 8.5.

A fourth object of the invention is to provide a mild, sulfated detergent of relatively low alkalinity and having an unusually high S03 content and negligible degree of unsaturation.

A fifth object of the invention is to provide an improved method of compounding a mild detergent.

A sixth object of the invention is to provide an improved process for compounding detergents whereby a higher degree of sulfation and lower alkalinity are obtained.

A seventh object of the invention is to provide a process for producing a sulfated fat-alkali soap detergent capable of producing abundant lather at a relatively low pH value.

Other objects of the invention will in part obvious and will in part appear hereinafter.

The foregoing and other objects may be obtained in accordance with the present invention by reducing to a minimum the skin-irritating substances present in the soap and by increasing the water-solubility characteristics of at least one of the ingredients. This may be accomplished by selection of the proper raw materials and by processing these materials as hereinafter disclosed. The resulting product is a soap even milder than castile soap and capable of producing abundant lather in soft, hard or salt waters. Its use is especially recommended in instances of soap-irritable skins, contact dermatitis, in-

fantile eczema, occupational dermatoses and soap-aggravative lesions. Its use is particularly beneficial in maintaining the skin in good order in certain occupations, as the practice of surgery, which require frequent and thorough washing of the skin. It will not cause further drying of skin which is already deficient in natural fats, nor will it further irritate pathological skin where cleansing is necessary. Since the improved soap neither irritates nor sensitizes normal skin, it may be used on skin which tolerates regular soaps as well as on skin which does not.

The terms fatty materials and fatty compounds are used herein to connote any fats, fatty oils, fatty acids, or fatty acid esters or mixtures thereof. Similarly, the expression tallow material is employed herein to indicate tallow, fatty acids produced from tallow and esters derived from tallow.

Fatty materials with predominantly from 16 to 22 carbons in the fatty acid chains are suitable for use in the present invention, but those of 1.6 or 18 carbon atoms are preferred. Since only one double bond of an unsaturated aliphatic group is saturated by the sulfating agent employed, substances having two or more double bonds in the aliphatic radicals are only partly saturated through sulfation in the process of the present invention. Although the irritating qualities of such compounds are thereby reduced, they are not completely nullified. Raw materials for the improved detergent are accordingly selected from fatty compounds comprising not more than minor proportions of acyl radicals with two or more double bonds or of acyl radicals having fewer than 16 carbon atoms.

In the present method, long-chain unsaturated fatty acyl radicals are saturated to a high degree with an agent which improves the insolubility in water. To reduce the effect of high alkalinity, it is proposed to adjust the pH value of the soap to between 7 .5 and 8.5 subsequent to saponification. The resulting product is consequently milder than soaps known heretofore by reason of the reduction or elimination of the irritating factors mentioned.

The invention accordingly comprises the several steps in relation to one or more of such steps with respect to each of the others and the composition of matter possessing the characteristics, properties and relation of components, all of which will be exemplified in the following detailed disclosure and the scope of the invention will be indicated in the claims.

In accordance with the present invention, suitable fatty materials are selected from animal, fish or vegetable oils, fats or waxes containing predominantly from 16 to 22 carbon atoms in the fatty acid chain and of which to have one double bond therein; or a variety of fatty substances may be blended to produce a mixture meeting these specifications. Unsaturated fatty compounds other than those having only one double bond should be kept to a minimum. Examples of the many suitable fatty materials include tallow, castor, corn, cod, cottonseed, menhaden, mustardseed, neats-foot, olive, peanut, rapeseed, rice bran, safflower, seal, sesame, soybean, sperm, teaseed, Whale and like oils, either in natural form or partially hydrogenated.

Natural tallows are greatly preferred and yield superior results in the process to be described hereinafter. The constituents of animal and fish tallows vary considerable in kind and as to proportions; however, the following is typical of beef tallow:

Fatty acyl radicals Parts by weigh;

It will be noted that beef tallow contains only minor proportions of the myristic acyl radical having 14 carbons and of the linoleic radical with its two double bonds. For the purposes of the present invention, tallow may be regarded as a mixture of the glycerides of 16 and 18 carbon fatty acids with half of the fatty acid radicals saturated and the other half containing one double bond.

In the preferred process, the tallow or other fatty material is first transesterified or esterified with methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol or a similar volatile aliphatic alcohol having a comparatively short carbon chain.

A small quantity of sodium, sodium alcoholate. other transesterification catalyst or acid esterification catalyst may be employed. The alkyl esters of fatty acids are isolated in the second step.

These esters are then treated with concentrated sulfuric acid at controlled temperatures to sulfate and saturate the esters to the highest possible degree. The saturated esters are unaf fected by the sulfuric acid treatment. In the case of methyl oleate the theoretical sulfation. will yield a 20.3% S03 content. In the laboratory practice of the present invention, sulfations approaching the theoretical content of S03 have been realized, and. while the figures in large-scale production are somewhat lower, they are still surprisingly high. Since tailow compounds gene erally have about 50% unsaturated components, an organic S03 content expressed in percentage of total dry, ash-free weight of sulfated tallow compounds should be doubled in representing the degree of sulfation in comparison with an S03 content of dry unsaturated compounds. We have discovered that higher sulfations are obtainable using a single naturally occurring fatty material than with an artificial blend simulating the natural material and composed of several fatty compounds. The principle underlying this effect is not known. In addition, it has been found that a higher degree of sulfation of an unsaturated fatty compound can be procured in a mixture containing substantial amounts of saturated fatty compounds than is possible by treatment of the unsaturated fatty substance alone. It appears that the dilution in this 'case of the unsaturated reactant with a saturated material increases the efficiency of the sulfation. We have also discovered that a high degree of sulfation can be obtained more consistently when the unsaturated fatty material is present in the form of an alkyl ester than when present as a glyceride or fatty acid. Here it appears that the lower viscosity of the esters in comparison to glycerides or fatty acids is a distinct aid in promoting sulfation. Thus, although esterification is optional in the present invention, thev employment of this step is highly preferred, especially in view of the well-know-nvariations in the composition of naturally occurring fatty materials,

The time of sulfation is also important as we have found that when sulfation is prolonged beyond about 60 to 90 minutes the organic S03 content is gradually reduced for the next few hours at least. When a mixture of equal weights of methyl oleate and commercial methyl stearate was treated with sulfuric acid, a portion which had been sulfated for one hour was found to contain 8.0 per cent organic S03 on the basis of the dry, ash-free total weight of fatty compounds after sulfation, while a portion treated for two hours contained only 7.7 per cent and a third portion contained 7.3 per cent after treatment for 4 hours. It should be borne in mind that materials of commercial or technical grades were employed in performin various experiments in connection with the present invention. Some of these raw materials are comparatively pure, while others are not. For example, commercial stearic acid is known to contain sizable proportions of other fatty acids, particularly palmitic acid. The temperature of the reaction mixture affects the reaction, for the equilibrium shifts with a rise in temperature and more S03 splits off from the organic sulfate in the reverse reaction to decrease the organic S03 concentration from that obtained at lower temperatures. Within limits, increasing the ratio of sulfuric acid to fatty materials will increase the degree of sulfation. In plant operations, all of these factors are carefully balanced in order to procure the best results at minimum expense.

In carrying out the sulfation operation, sulfuric acid containing 98 per cent H2804 is mixed with the fatty compounds at a controlled rate in order to prevent the temperature from rising far above room temperature. The product is then washed to remove the excess sulfuric acid. Sodium chloride is used in the wash solution-to aid in the separation of the wash water and the fatty mixture; and the wash water is preferably chilled. After separation, the fatty component still contains some water and mineral acid. This mineral acid is then neutralized by the addition of an alkali in slight excess. After panning overnight to separate the sodium sulfate and water from the fatty phase, this water is drawn off. Further alkali is then added to bring the total alkali content to about 0.5 to 1.5 per cent to prevent the sulfate radical from splitting off from the fatty molecule and also to neutralize any remaining mineral acid. At this stage, a considerable amount of free fatty acids and unsaponified fatty acyl groups are still present. In view of the saponification step following, the quantity of alkali used here is not critical. The sulfated mixture of fatty compounds is next saponified by treating with the proper quantity of a 50 per cent aqueous alkali solution. In this reaction the alkali replaces the alkyl radical at the end of the chain of the fatty acid compounds and replaces the hydrogen atom in the OSO3H group attached to the previously unsaturated fatty compounds. The short-chain alkyl radical split off from the esters forms its corresponding alcohol, which is distilled oil. and recovered. In carrying out the process described above and in the examples, it was found that suitable materials were consistently sulfated to an S03 content of 9.0 per cent or more in the case of tallow materials (18% on a sulfated ingredient basis), and others to at least 16.0 per cent based on the weight of the sulfated ingredient of the mixture.

When fatty esters or glycerides are the raw materials, it is essential to carry the saponification to completion in order to convert all of the esters to be construed in a limiting sense.

into soaps, that is, alkali salts of the fatty acids. The conventional finishing steps following saponification are used to separate the soaps formed. The pH value of these soaps ranges from about 9 to 11 and it may be said that 10 is a fair average value. To lower the alkalinity of these soaps, a mineral acid as, for example, concentrated hydrochloric acid (36 per cent), is used to reduce the pH to the range of 7.5 to 8.5. The best results are secured with the pH adjusted to between 8.0 and 8.5. The addition of acid forms a minor proportion of fatty acids in the soap mixture. A similar result may be secured where the raw materials are fatty acids rather than fatty esters or glycerides by saponifying directly to a pH of only 8.0 to 8.5. However, in the case of the esters and glycerides, it is essential to completely saponify and then add mineral acid to reduce the alkalinity, in order to obtain satisfactory lathering at the desired lower pH. It has been found that equivalent results are not obtained With esters and glycerides by merely directly saponifying to a pH of 8.0 to 8.5 as such a product produces little or no lather. From this it appears that the presence of fatty esters or glycerides in the mixture inhibits the formation of a satisfactory lather.

At this stage, any addition agents such as germicides, antiseptics, perfumes or superfatting agents such as lanolin may be added. While super fatting agents such as lanolin may tend to replace part of the oil removedfrom the skin in washing, it is debatable whether these substances render the soap any milder. Thereafter, the

processed material is poured into standard soap frames, slabbed, barred, slugged and finally pressed into cakes or milled, extruded, cut in bars and stamped in the customary manner. I

The product is a milder and more efficient detergent than those of the prior art by reason of its consistently higher degree of sulfation, lower alkalinity and the absence of any substantial quantities of short-chain aliphatic compounds and organic radicals originally containing more than one double bond. It is desired to point out that the higher sulfation not only makes the soap milder by minimizing the quantity of unsaturated components, but also increases the wettin properties of the detergent and renders it more effective in salt and hard waters. It is to be understood that the soap of the present invention, when used in soft Water, possesses similar advantages over the known detergent compositions.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following examples, which are given merely to further illustrate the invention and are not All parts given are by weight.

Example I TRANSESTERIFICATION H2804) previously chilled to 13 C. are added slowly and intermittently over a period of approximately 1%.; hours to prevent the maximum temperature from rising above 23 C. The reaction mass is then stirred for about 15 minutes and poured into a wash solution cooled to 6 C. and consisting of 1'7 parts of sodium chloride in 200 parts of water. After agitating for five minutes, the mixture is permitted to settle for approximately 15 minutes. The mixture separates into layers and the aqueous component containing salt water and unreacted sulfuric acid is drawn off. Sufficient alkali is then slowly added to the sulfated tallow esters to neutralize any remaining sulfuric acid. A slight excess of the base, amounting to 0.25 per cent of the total weight of the reaction mixture over the quantity required to neutralize the mineral acid, is employed. While sodium hydroxide is used in this step, any other alkali may be substituted. By adding the alkali slowly, the maximum temperature is held below 41 C. At this stage, only the mineral acid is neutralized, for no substantial saponification of the esters or neutralization of any fatty acids present occurs. The material is then permitted to pan overnight, and the salt water separated is drawn off. More sodium hydroxide is now added. to bring up the total alkali content to 1.5 per cent of the entire mass. Upon analysis, the fatty reaction products are found to have:

Organic S03 9.5 per cent (dry, ash-free basis) Sapom'fication value 165 Acid value 15 Due to the absence of mineral acids, no diniculty is encountered with S03 splitting off from the sulfated esters. In repeating the sulfation with esters obtained from a different batch of tallow, the organic S03 content was 9.0 per cent, Still another batch yielded an S03 content of 10.0%. It is probable that the difference in S03 content is due in large part to different proportions of unsaturated constituents in the tallows.

SAP ONIFICATION One hundred thirty-five (135) parts of the sulfated mixture (about 100 parts of sulfated esters with 35 parts water) are saponified completely by heating with approximately 15 parts of a 50 per cent caustic soda solution. The pH value of the soap produced is found to be about 10; if a softer soap is desired, caustic potash may be employed as the alkali here.

ACIDIFICATION One hundred (100) parts of the sulfated soap are then treated with about five parts of hydrochloric acid (36 per cent H01) to bring the pH value of the soap within the range 8.0 to 8.5.

FINISHING The soap is poured into standard soap frames, slabbed, barred, slugged and finally pressed into finished cakes in the conventional manner. An alternative method includes drum-drying, milling, plodding, extruding, cutting into slugs and stamping into cakes. The yields are found to be substantially those of theory. The product is very mild and an excellent detergent even in salt and hard waters.

Example If A sulfated soap is prepared in the same manner and with the same ingredients as in Example I.

FINISHING Before framing, 1 to 2 per cent of dihydroxyhexachlordiphenyl methane is thoroughly mixed into the soap. The soap mixture is then finished in the manner set forth in the previous example. The resulting soap possesses excellent germicidal qualities in addition to its mildness and suitability for use in hard or soft water.

Example III Another excellent medicinal soap is prepared by incorporating powdered sulfur in the sulfated soap in place of the dihydroxyhexachlordiphenyl methane of Example II. Any quantity of sulfur up to about 15 per cent of the weight of the soap may be used to obtain the preferred therapeutic strength.

Example IV SULFATION One hundred (100) parts of animal tallow are stirred into 100 parts of sulfuric acid (98% H2S04) at 0 C. as rapidly as possible While maintaining the temperature below 20 0. without refrigeration. About 30 minutes is required for the addition of the fats. Thereafter the mixture is agitated for an additional 15 minutes, and dropped into a wash solution consisting of parts of sodium chloride in 700 parts water and 300 parts ice. The temperature rises to about 28 C. in this operation, The mixture is stirred for five minutes and allowed to settle for 15 more. The salt water and excess acid separate and are drawn off. Soda ash is added with stirring until the total alkali content is about 0.25 per cent, thereby neutralizing all excess mineral acid. The maximum temperature encountered in this reaction is 45 C. After panning overnight the separated salt water is withdrawn, and the total alkali content increased to 0.5 per cent by addition of either caustic soda or soda ash. The batchis found by analysis on the ash-free, dry Weight basis to contain:

Organic S03 9.5 per cent Saponification value 165 Acid value 15 To obtain the same organic S03 content as in Example I it is found necessary to employ approciliimately twice as much concentrated sulfuric aci The saponification, acid treatment and finishing steps of Example I are repeated to produce substantially identical soap.

Example V Tallow is saponified completely with caustic soda or any other suitable alkali to produce a mixture of sodium soaps. After separation from the glycerine in the customary manner, these soaps are then reacted while stirring with hydrochloric or other acids to form sodium chloride and the fatty acids of the tallow. The stirring is discontinued and the fatty acids allowed to separate from the salt water which is then drawn on.

SULFATION One hundred parts of the tallow fatty acids are added to 100 parts of chilled sulfuric acid (98% H2804) over a period of about hour. The procedure and quantities of the agents in the previous example are also employed here. Upon adjusting the total alkali content subsequent to panning, analysis of the reaction prodnets on a dry weight base yields the following figures:

Organic SO3 1 9.5 per cent (ash-free basis) Total alkali 0.5 per cent Saponification value 165 Acid value 160 It should be noted that while the tallow fatty acids may be sulfated to a high degree as readily as the tallow of the preceding example, both require considerably more sulfuric acid than is required for the tallow esters of Example I.

SAPONIFICATION The sulfated fatty acids, still containing approximately 25 per cent water from the above reactions, are not completely saponified in this instance, as a 50 per cent caustic soda solution or other aqueous alkali is added only until the pH value is between 8.0 and 8.5. No acidification step is necessary here.

FINISHING The soap is processed through the same finishing steps given in connection with Example I to produce a product of the same mildness and equal lathering qualities in all typesof water.

Example VI ESTERIFICATION One hundred (100) parts of commercial stearic acid are treated with 30 parts of methyl alcohol,

in the presence of 0.3 part of p-toluene sulfonic acid as a catalyst, b refluxing. The resulting methyl stearate usually contains appreciable quantities of methyl palmitate. ()ne hundred (100) parts of oleic acid are esterified with 14.5 parts of methyl alcohol by refluxing in a similar manner using 3.0 parts of concentrated sulfuric acid as the esterification catalyst. Upon completion of the refluxing each ester is separated from the catalyst and water formed during the reaction, and equal quantities of methyl stearate and methyl oleate are thoroughly mixed. By titration, the iodine number of the ester mixture is found to be approximately 45.

SULFATION Fifty-five (55) parts sulfuric acid at room temperatures are added at a rate of approximately 1 part per minute to 100 parts of the mixed which had previously been cooled to C. The highest temperature obtained in the reaction is 22 C. After stirring for an extra minutes, the reaction products are poured into a solution of 17 parts sodium chloride in 200 parts of water. The washing mixture is agitated for 15 minutes and then allowed to settle for 15 minutes. The maximum temperature during the washing is 28 C. After drawing ofi the Water and excess acid, the sulfated methyl esters are treated with caustic soda solution to neutralize the excess mineral acid and adjust the total alkali content to 0.25 per cent of the total Weight of the reaction mixture. In this step the highest temperature reached is 35 C. The salt water is then separated and withdrawn, and the batch is panned overnight. A further quantity of caustic soda solution is added at this point, The fatty residue is analyzed and found to include on a dry basis:

Organic S03 8.0 per cent (ash-free basis) Total alkali 1.1 per cent Saponification value 165 The saponification, acidification and finishing procedures used here are the same as those described in Example I.

Example VII FINISHING Prior to framing the soap of the previous example, two parts of lanolin are thoroughly stirred into each parts of soap. The lanolin functions as a superfatting agent and various other such agents may be substituted if preferred.

Since certain changes in carrying out the above process and certain modifications in the composition which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all the generic and specific features of the invention herein described and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween: and that they are intended to be inclusive in scope and not exclusive, in that if desired, other materials may be added to our novel composition of matter herein claimed without departing from the spirit of the invention. Particularly it is to be understood that in said claims, ingredients or components recited in the singular are intended to include compatible mixtures of said ingredients wherever the sense permits.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

l. A mild nonirritating skin-cleansing composition composed essentially of a foamable mixture of an alkali-metal stearate soap and an alkali-metal salt of a sulfated oleate with an S03 content of at least 16.0 percent based on the ash-free dry weight of the sulfated oleate, the oleate radicals comprising between approximately one third and approximately two thirds of the total number of acyl radicals in the mixture, and the said mixturehaving a pH value between approximately 7.5 and approximately 8.5.

2. A mild nonirritating skin-cleansing composition composed essentially of a foamable mixture of an alkali-metal stearate soap and an alkalimetal salt of a sulfated oleate with an S03 content of at least 16.0 percent based on the dry Weight of the oleate, the oleate radicals comprising between approximately one third and approximately two thirds of the total number of acyl radicals in the mixture, and the said mixture having a pH value between approximately 8.0 and approximately 8.5.

3. A mild nonirritating skin-cleansing composition composed essentially of a foamable mixture of an alkali-metal stearate soap and an alkali-metal salt of a sulfated oleate with an S03 content of at least 16.0 percent based on the ashfree dry weight of the oleate, the oleate radicals comprising approximately one half of the total number of acyl radicals in the mixture, and the said mixture having a pH value between approximately 8.0 and approximately 8.5.

4. A mild nonirritating skin-cleansing composition comprising a foamable alkali-metal soap of a sulfated tallow material, thesulfated tallow material containing at least 8.0 percent S03 based on the ash-free dry weight, and the soap having a pH value between approximately 7.5 and approximately 8.5.

5. A mild nonirritating skin-cleansing compo- 11 sition comprising a foamable alkali-metal soap of a sulfated tallow material, the sulfated tallow material containing at least 9.0 percent S03 based on the ash-free dry weight, and the soap having a pH value between approximately 8.0 and approximately 8,5.

6. A mild nonirritating skin-cleansing QQmQQ'! sition comprising a foamable alkali-metal soap, of a sulfated fatty material having acyl radicals containin essentiall from 16 to arbon atoms. the s ap avin a p va ue betwe n prox mately 7.5 and approximately 8.5,, the sulfated material being derived from a fatty raw material mprisin b ween. approximately o e t rd a approx matel two t i s by weight o un rated matter, and the, initially unsaturated matter being sulfated to an organic SO; content of r at east 16.0 percent based, on t e sh-free d y Weight after sulfation.

7. A composition as defined in laim 6 ncludi a small proportion of a germicide.

8. A process for producing a mild nonirritatin detergent composition which comprises reacting, at a temperature sufficiently low to prevent excessive decomposition of organic sulfates, sulfuric acid in excess with esters of a volatile monohydric lower aliphatic alcohol and a mixture of essentially 16 to 22 carbon atom fatty acids to an organic S03 content of at least 16.0

percent based on the ash-free dry weight after I? sulfation of the initially unsaturated fatty acids, the fatty acids initially containing between approximately one third and approximately two thirds by weight of unsaturated fatty acids, addin suflicient alkali to the reaction products to neutralize any unspent sulfuric acid and to saponify completely the esters, and thereafter adding sufficient mineral acid to the saponified mass to reduce the pH value thereof to between 7.5 and 8.5.

9. A process as defined in claim 8 in which the mineral acid is added in quantity sufiicient to reduce the pH value of the saponified mass to between 8.0 and 8.5.

Number 10. A process as defined in claim 8 in which the esters comprise a stearate and an oleate.

11. A process as defined in claim 8 in which the esters comprise esters of tallow.

12. A process as defined in claim 8 in which the alcohol is methanol.

13. A process for producing a mild nonirritating detergent composition which comprises reacting, at a temperature sufliciently low to prevent excessive decomposition of organic sulfates. sulfuric acid in excess with the esters of at naturally-occuring tallow and a volatile monohydric lower aliphatic alcohol to an organic SO: content of at least 9.0 percent based on the ashfree dry weight of tallow esters after sulfation, adding sufilcient alkali to neutralize any unspent sulfuric acid and to. completely sapcnify the tallow esters, and addin a mineral acid in suf ficient quantity to the saponified mass to reduce the pH value thereof to between 8.0 and 8.5.

JOHN J. MISKEL. LOUIS RASSNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Bertsch Sept. 15, 1931 Bertsch July 31, 1934 Bertsch A July 31, 1934 Miles May 24, 1938 Abramowitz Nov. 19, 1940 Dombrow Nov. 26, 1940 Guild Dec. 1, 1942 Cook Mar. 13, 1945 Cunder Jan. 21, 1947 FOREIGN PATENTS Country Date Great Britain Sept. 30, 1940 OTHER REFERENCES Martin: Modern Soap and Detergent Industry, 1931, vol. II, sec. 3, pp. 21 and 22.

Number 

1. A MILD NONIRRITATING SKIN-CLEANSING COMPOSITION COMPOSED ESSENTIALLY OF A FOAMABLE MIXTURE OF AN ALKALI-METAL STEARATE SOAP AND AN ALKALI-METAL SALT OF A SULFATED OLEATE WITH AN SO3 CONTENT OF AT LEAST 16.0 PERCENT BASED ON THE ASH-FREE DRY WEIGHT OF THE SULFATED OLEATE, THE OLEATE RADICALS COMPRISING BETWEEN APPROXIMATELY ONE THIRD AND APPROXIMATELY TWO THIRDS OF THE TOTAL NUMBER OF ACYL RADICALS IN THE MIXTURE, AND THE SAID MIXTURE HAVING A PH VALUE BETWEEN APPROXIMATELY 7.5 AND APPROXIMATELY 8.5.
 4. A MILD NONIRRITATING SKIN-CLEANING COMPOSITION COMPRISING A FOAMABLE ALKALI-METAL SOAP OF A SULFATED TALLOW MATERIAL, THE SULFATED TALLOW MATERIAL CONTAINING AT LEAST 8.0 PERCENT SO3 BASED ON THE ASH-FREE DRY WEIGHT, AND THE SOAP HAVING A PH VALUE BETWEEN APPROXIMATELY 7.5 AND APPROXIMATELY 8.5. 